What it means
The switching/check valve in the secondary air injection plumbing on bank 1 is stuck in the open position. With the valve permanently open, exhaust gas can back-feed into the air pump and corrode it, while the downstream O2 sensor sees ambient air constantly.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The secondary air injection switching valve for bank 1 controls airflow into that bank's exhaust during cold starts to help the catalyst warm up. This code sets when the valve remains open when it should close, allowing exhaust to flow back through the air injection plumbing and potentially damage the pump.
Common causes
Most likely first.
- Switching valve stuck open by carbon or corrosion
- Carbon or debris buildup preventing free movement
- Component wear with age - mechanical play
Symptoms
- Check engine light on
- Rough or elevated idle during cold start
- Reduced engine performance
- Unusual air-pump noise
How to diagnose it
- Use a scan tool to check freeze-frame data and command the bank 1 secondary air system on and off, noting whether the valve response and oxygen-sensor behavior change.
- With the engine cold and off, inspect the bank 1 switching valve and connected air pipes for carbon, corrosion, heat damage, or evidence of exhaust backflow.
- Check the valve's connector, wiring, and any vacuum-control line used on this vehicle for loose connections, damage, or leaks.
- Test whether the bank 1 valve moves and seals when commanded, using the vehicle's service procedure rather than applying unverified pressure or power.
- If the valve is stuck open, inspect the air pump and related plumbing for corrosion or exhaust damage before returning the system to service.
Common fixes
- Repair a damaged connector, wiring, or leaking valve-control line for bank 1.
- Clean carbon or debris from the bank 1 switching valve if the service procedure permits.
- Replace the bank 1 switching valve if it cannot close and seal reliably.
- Replace a secondary air pump damaged by exhaust backflow after correcting the stuck-open valve.
Can I keep driving?
Avoid prolonged driving if the air pump is noisy or there is evidence of exhaust backflow, and arrange repair soon because the bank 1 pump can corrode or fail. The cold-start emissions fault can also cause rough or elevated idle and an emissions test failure.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.